Reverse flow aquarium filter device

ABSTRACT

A filter device in the form of a gravel supporting tray structure for use, particularly in an aquarium water purification system employing a tertiary filter cycle utilizing a shallow gravel trickling filter with underwater aeration and sedimentation followed by anaerobic action and final tertiary cycle.

United States Patent 119.1

Field of Search ..210/1 69, 500

White 1*March 13, 1973 1 REVERSE FLOW AQUARIUM FILTER [56] References Cited EVICE D UNITED STATES PATENTS [75] Inventor: Eugene B. White, Oak Park, Ill.

3,578,169 5/1971 White ..2l0/l69 Asslgneei Flue" l (31110380, 2,961,710 11/1960 Stark....' ..210 500 3,472,381 10/1969 HalperLL. ..2l0/169 Kelle ..210/169 X Notlce. The port10n of the term of th1s 3529'574 9/1970 y I patent subsequent to y 11" 1988, 3,540,591 11/1970 Yamazakl ..210/169 1 has been dlsclalmed Primary ExaminerReuben Friedman [22] Filed: May 10, 1971 Assistant Examiner-T. A. Granger [21] APPL NOJ 141,680 Attorney-Hill, Sherman, Meroni, Gross & Simpson Related [1.8. Application Data [57] ABSTRACT [60] Continuation-impart of Ser. No. 67,648, July 31, A filter device in the form of a gravel supporting tray 1970, abandoned, which is a division of Ser. No. structure for use, particularly in an aquarium water 8051274 March 7, 1969 31578,]69- purification system employing a tertiary filter cycle utilizing a shallow gravel trickling filter with un- [52] US. Cl ..2l0/169 Ciel-water aeration axd Sedimentation followed by Int. Cl. ..E04|l 3/20 anaerobic action and finaltertiary cycle 18 Claims, 17 Drawing Figures PATEHH UW 1 31013 SHEET 2 [1F 6 I l l 7 2.5/4,

1- REVERSE FLOW AQUARIUM FILTER DEVICE BACKGROUND OF THE INVENTION filter structures utilizing charcoal or the like have been employed in small aquariums, for example from 5 to 40 gallons capacity, such filters usually employing a case in which bulk materials were placed, with the filter structure being disposed in the aquarium and the water circulated through the filter by means of a small air pump operative to simultaneously provide some aeration of the water. Filters of this type usually employed a charcoal in the'form of relatively large or coarse pieces, which were placed in the filter with a layer of glass wool or the like which formed a screen-likestructure, which was relatively fine compared with the charcoal and was operative to trap particles of debris in the water being circulated, Filters of this type have a relatively shortfiltering cycle, tending to rather quickly slime up, and to replace the filtering materials it was necessary to remove the filter structure from the tank, clean such structure and repack it with bulk materials, an operation that was messy and disagreeable. In addition, relatively poor filtering action was achieved which was obvious from an inspection of the aquarium. At the same time, the debris or organic matter settled at the bottom of the tank, tending to fill the interstices in the usual aquarium gravel placed on the floor of the tank. In order to improve this condition, it was common practice to also maintain one or more scavenger fish in the aquarium which would live off of such matter and tend to reduce quantities thereof within the aquarium. In an effort to improve aquarium conditionsso-called undergravel systems have been proposed in which the aquarium gravel is not placed upon the floor or bed of the tank, but upon a shallow tray disposed on the tank bottom whereby the layer of grave] is elevated to provide a water chamber therebelow from which so-called filtered waterwas withdrawn and returned to the aquarium water. This type of arrangement was normally employed without additional filter means, or if an additional water treatment was desired, a small additional charcoal unit was disposed in the water on the end of other debris in the gravel, which could readily be ascertained by merely agitating the tank water adjacent the bottom of the tank which would result in a murky cloud of debris.

One form of tray structure is illustrated in U.S. Pat. No. 2,935,199 granted on May 3, 1960 to Allan H. Willinger, while a filter which may be employed therewith is illustrated in U.S. Pat. No. 3,145,168,

granted on Aug. 18, 1964 to Victor E. Scafuro. The present invention is directed to a purification or filter system and filter structure which eliminates the disadvantages of the prior devices.

BRIEF SUMMARY OF THE INVENTION The invention is directed to a water purification system employing an under-gravel trickling filter, utilizing a tray structure somewhat similar to that heretofore employed but adapted to contain a shallow bed of filter material upon which the usual aquarium grayel may be placed, with the tray structure being so constructed that a relatively uniform water flow through the filter bed is achieved.

Two examples of filter constructions are presented, one of which is of the external type adapted to be disposed exteriorly of the aquarium water, as for example supported on one wall edge of the tank, and the other example being an internal type adapted to be disposed directly in the tank water. For very small tanks, the internal embodiment may be employed without the additional under-gravel trickling filter. The arrangement is such, irrespective of the particular type of filter employed, that bio-filtration is achieved with a continuous circulation of settled debris at a high rate through the shallow filter bed for biological oxidation and final water polish through the external or internal filter structure, thus resulting in a tertiary cycle. The primary cycle thus results from the sedimentation and aeration taking place in the shallow under-gravel filter with the water flow therethrough, having been aerated by the same air pump which produced the water circulation. The oxygen content oxidizes the organic matter present which is drawn through the aquarium gravel and oxidized at the interface between the latter and the layer of filter material therebelow. At the same time the anaerobic action in the filter bed absorbsorganic compounds and decomposes them to gases, a characteristic of an underwater gravel filter of this type being the natural unloading of the humus-like film which accumulates in the filter bed, thus preventing clogging of the under-gravel filter with colloidal and suspended matter plus portions of the soluble organic substances concentrate at the trickling filter interface where such absorbed substances are attacked by enzymes and bacteria, and ammonia thus liberated is subsequently oxidized.

The stabilized effluent of the trickling filter then flows through the under drainage system provided to the final filtering system which effects the final clarification and purification of the water prior to its discharge back into the tank. In the external construction the eductor pump is disposed between the under drainage system'and the external filter structure, while in the internal construction the pump is disposedatthe discharge side of the internal filter system whereby it draws the water from the underwater drainage system through the filter from which it is discharged through the pump back to the tank.

In the preferred embodiment of the underwater drainage system, the tray structure is constructed in two sections, one of which forms the supporting surface for the shallow layer of filter material, upon which the aquarium gravel is disposed. The other section forms a supporting structurefor the first andat the same time is constructed to provide a substantially uniform water flow through the filter material throughout the area of the filter bed.

The external filter structure, in addition to its advantage of accessibility for maintenance, also provides the advantage of utilizing the natural flow of the water to provide the pressure head through such filter and is so constructed that in the event the filter becomes clogged the water flow by-passes such filter, returning the water to the tank whereby the undergravel filter can be retained in operation.

' The present invention therefore has among its ob jects the production of a filter system which is simple in construction, relatively inexpensive and yet will provide superior filtering efficiency.

Another object of the invention is the production of such a filter system which makes use of both anaerobic and aerobic action. A further object of the invention is the production of a filter structure, either of the external or internal type, in which the filtering materials may be permanently disposed in a removable and replaceable cartridge, whereby replacement of the filter material may be readily and very simply accomplished, merely by removing the old cartridge and substituting a new one therefor, completely eliminating any messy replacement operation.

Another object of the invention is the production of a shallow'under-gravel trickling filter arrangement BRIEF DESCRIPTION OF THE DRAWINGS In the drawings wherein like reference characters indicate like or corresponding parts:

' FIG. 1 is a perspective view of apart of the rear por- I tion of an aquarium, illustrating an external type filter mounted on the upper edge thereof and a portion of the tray structure for the under-gravel trickling filter and underwater drainage system;

FIG. 2 is a top plan view of the supporting tray for the filter material of the under-gravel tray structure;

FIG. 3 is a bottom view of the under-gravel tray structure; i

FIG. 4 is a sectional view taken approximately on the line IV-IV of FIG. 2;

' FIG. 5 is a sectional view taken approximately on the line V\/ of FIG. 2;

FIG. .6 is a longitudinal sectional view through the external filter structure, taken approximately on the line VI-VI of FIG. 7, with the filter cartridge being illustrated in elevation;. v

FIG. 7 is a transverse sectional view, taken approximately on the line VII-VII of FIG. 6;

FIG. 8 is a perspective view of the filter cartridge employed with the external filter illustrated in FIGS. 1, 6 an FIG. 9

is a perspective view of an internal filter embodying the invention;

FIG. I0 is a section taken approximately on the line X-X of FIG. 11, with the major portion of the filter cartridge therefor being illustrated in elevation and a portion thereof broken away to show the details of construction thereof;

FIG. 11 is a transverse sectional view taken approximately on line XI-XI of FIG. 10;

FIG. 12 is a vertical section taken approximately on the line XII-XII of FIG. 11;

FIG. 13 is a sectional view similar to FIG. 12, illustratingthe construction of the filter illustrated in FIG. 9 where it is to be employed with an under-gravel trick ling filter;

FIG. 14 is a top plan view similar to FIG. 2 of a modified filter with portions thereof broken away to show details of construction;

FIG. 15 is a sectional view taken approximately on line XV-XV of FIG. 14;

FIG. 16 is a sectional view taken approximately on the line XVIXVI of FIG. 14; and

FIG. 17 is a sectional view through two adjacent tray structures such as illustrated in FIG. 14, illustrating the connection thereof and corresponds to a section taken approximately on the line XVII-XVII of FIG. 14.

DETAILED DESCRIPTION OF THE INVENTION For clarity the description will be presented in four parts. The first being general and briefly covering the basic components; the second being a detailed description of the under-gravel filter; the third including details of the external filter structure; the'fourth including details of the internal filter structure which may be designed for utilization with or without the undergravel filter; and the fifth a detailed description of a modified form of under-gravel filters.

GENERAL CONSTRUCTION Referring to FIG. 1, the reference numeral 1 indicates generally an under-gravel tray structure adapted'to be placed on the bottom of the aquarium tank A and cooper'able with an external filter structure, indicated generally by the numeral 2, two such tray structures being illustrated,.disposed in abutting relation and each connected with the filter structure 2 by an eductor pump assembly indicated generally by the numeral 3, one pump structure being provided for each of the trays.

As will hereinafter be described in greater detail, each tray structure is adapted to form the supporting member for a layer of filter material such as particles of anthracite or quartz, which if desired may be suitably activated with purification materials in a known manner, upon which layer the usual aquarium'gravel is to be disposed. Aquarium water, after passing through v the gravel and the filter material, is drawn from the bottom side of the tray 1 by means of the pump 3 into the filter structure 2 in which it is further filtered and returned to the tank through a discharge spout 4.

Where an internal filter structure is employed the.

pump.may be constructed as a part thereof and the entire assembly disposed within the tank with the water inlet of the filter structure being constructed for cooperation with anunder-gravel filter or constructed to receive water directly from the tank adjacent the bottom thereof. I

THE UNDER-GRAVEL FILTER Referring to FIGS. 2 through 5, the under-gravel filter structure 1. is constructed in the form of a tray having an upper section 5 and a lower section 6. The lower section 6 comprises peripheral walls 7 between which extends a horizontal wall or floor 8, the latter being provided with a plurality of apertures or openings 9 therein as illustrated in FIG. 3, in which only a part of the openings 9 are illustrated merely to indicate the proportioning thereof. The openings adjacent the right hand peripheral wall 7 are illustrative of the general spacing in proportioning throughout the wall 8, and as is illustrated in FIG. 3 in dotted lines the lower section 6 is provided with a plurality of ribs 11 which are provided merely to give support to the central portion of the floor 8. The upper right hand corner of the tray sec tion 6, as viewed in FIGS. 2 and 3 carries the base structure of the pump 3 which, as illustrated in FIG. 5, is provided with tubular extensions 12 and 13 forming receiving bores for the pump discharge tube 14 and the air inlet tube 15, the latter being operatively connected at their lower ends by an air discharge port 16. Also communicating with the lower end of the discharge tube 14 is a bore 17 located in the floor 8. To facilitate fabrication of this structure, the portions 12 and 13 may be formed as a separate piece which is suitably cemented or otherwise secured to the floor 8 to provide a finished construction as illustrated in FIG. 5. As will be apparent from a reference to FIG. 4, the air discharge port 16 is generally rectangular in transverse cross-section and has an area which is less than that of the tube 15 whereby air discharged into the lower end of the water discharge tube 14 has an increased velocity. In operation, air is discharged from the bottom of the tube 15 through the port 16 and flows upwardly through the tube 14 drawing water from below the floor 8 through the opening 17, providing a very efficient pumping action with which is increased in the present construction by the provision of a shoulder or extension 18 which extends laterally below the tube 14 and eliminates any tendency of air discharged from the port 16 to pass downwardly through the opening 17. In the embodiment illustrated, the shoulder 18 is formed by employing an off-set or eccentric bore 17 having a diameter which is less than that of the tube 14.

The upper tray section 5 is provided with an inclined floor 21 which slopes toward the pump 3 whereby the highest portion of the floor is adjacent the lower left hand corner, as viewed in FIG. 2. Extending upwardly from the floor 21 are a plurality of partition ribs 22, the top edges of which are disposed substantially in the plane of the top edges of the peripheral walls 7 of the lower section with each partition rib extending along a portion of the floor which is uniformly spaced from the floor 8 of the lower section. As will be apparent from FIGS. 2 and 4, the floor 21 is provided with a plurality of slots 23 therein which extend horizontally, as viewed in FIG. 2, and are arranged in columns whichextend entirely across the face of the section (only a portion of the slots being illustrated in FIG. 2). As shown in FIG. 4 the slots 23 have downwardly diverging side walls whereby the widthof each slot is less adjacent the upper face of the floor 21 than adjacent the bottom face thereof, with the width of the slots in their narrow direction being less than the smallest particle size of filter material which is to be supported thereby.

The upper section 5 preferably is provided with a peripheral supporting wall 24 and a plurality of intermediate ribs 25 which, in the embodiment illustrated, are disposed directly below corresponding ribs 22 as will be apparent from a reference to FIG. 2. In the particular embodiment illustrated, the ribs 11 of the lower section and the ribs 25 of the upper section have no operational function but are operative merely to provide adequate support for the floors 8 and 21 respectively.

As illustrated in FIG. 4 filter material 26 is adapted to be disposed directly upon the floor 21 with the upper surface of the filter material being substantially flush with the upper edges of the peripheral walls 7 and ribs 22, with a layer of aquarium gravel 27 being disposed thereupon and covering the bed of filter material aswell as any other exposed portions of the tray structure 1.

In operation, water may pass through the layer of gravel 27, through the layer of material 26 of the trickling filter passing through the slot 23 and openings 9 in the floor 8, into the chamber formed by the bottom 28 of the aquarium A and the lower portion of the section 6, from which the water may be drawn by the pump 3 through the opening 17and discharged from the tube 14.

THE EXTERNAL FILTER Referringto FIGS. 1, 6, 7 and 8, the external filter structure comprises a hollow body structure or casing, indicated generally by the numeral 31, having a frong wall 32, a rear wall 33, a bottom wall 34 and the end walls 35 with the upper side of the casing being open and adapted to be partially closed by a removable cover member 36.

As illustrated in FIGS. 6 and 7, the interior of the casing 31 is divided by a partition wall 37 into a water inlet chamber 38 and a water filtering chamber 39 in which is disposed a filter cartridge 41, illustrated in FIG. 8. The body 31 is also provided with a forwardly disposed portion 42 over which the cover 36 extends, and which has a bottom wall 43 provided with two downwardly extending tubular water inlet fittings 44 which are adapted to receive the upper ends of a pair of pump tubes 14, assuming two pumps are employed as illustrated in FIG. 1. If the filter structure is utilized with only a single pump, the unused member 44 may be suitably closed with a rubber plug or the like. The portion 42 is laterally divided by, a partition wall 45 disposed intermediate the two inlet fittings 44 with the upper edge of the engaging partition wall and secured to a water directing or splash member 46, whereby water discharged into the structure is directed into the water-receiving chamber 38.

As illustrated in FIG. 8, the filter cartridge 41 isconstructed of plastic or other suitable material and is of generally rectangular shape having side walls 47 and end walls 48 of such lateral dimensions that they are generally complemental to the adjacent side and end walls of the water-filtering chamber 39. In the embodiment illustrated, the end walls 48 are extended upwardly to form handles 49 by means of which the cartridge may be inserted or removed from the body 1,

with the inserted cartridge being adapted to rest on a plurality of projections or abutments 51, only one of which is illustrated, which extend inwardly from the respective walls 32, 33 and 35 which cooperate with the partition wall 37 to define the chamber 39.

As illustrated, the bottom 52 of the cartridge 41 is provided with a plurality of slots 53 therein through which water may flow into the cartridge, and disposed in the cartridge adjacent the bottom thereof is a layer of suitable material as for example a porous foam plastic 54 which forms a retaining member for relatively large particles of filter material 55 disposed in the cartridge. Covering the exposed face of the layer of filter material 55 is a screen 56, which may be constructed of perforated plastic or other material and is adapted to separate a layer of relatively small particles of filter material 57 from the material 55 with the adjacent open side (the upper side as viewed in FIG. 1) of the cartridge being covered with a layer of porous foam plastic material 58, which may be of the same material as the layer 54 which is suitably secured to the side walls of the cartridge. As the pores of the material 58 are smaller in size than the particle size of the material 57, the filter material is effectively retained in operative position in the cartridge. The cartridge is also provided with a laterally extending lip 59 which overlies the adjacent face of the discharge spout 7 when the cartridge is in operative position.

The partition wall 37 functions as an inverted weir and is provided with openings 61 at the bottom thereof through which water may flow from the water inlet chamber 38 into the chamber 39 directly below the cartridge and thus may enter the openings 53 formed in the bottom of the cartridge. Referring to FIG. 6 it will be noted that the lip 59 and the discharge spout 7 are disposed below the upper face of the wall 43 with the difference in height therebetween representing the head of water exerting pressure on the water in the filter cartridge to provide a minimum pressure head at all times.

In the event the cartridge should become clogged and the flow therethrough fall below an amount sufficient to accommodate the in flow into the chamber 38, the water level in the latter will rise until it reaches the top of the partition wall 37 at which it may readily over- 7 flow into the chamber 39 and be discharged from the spout 7, the wall 37 thereby functioning also as a safety weir eliminating any possibility of overflow other than a return flow into the aquarium tank.

FIG. 1 illustrates the connection of two filter trays 1 to the external filter 2 by means of respective pumps 3, the air tubes of which are adapted to be connected by flexible tubes 63 to air pumping means for supplying air to each of the pumps and in operation, each of the trays 1 would be filled with a layer of activated filter the gravel bed and anaerobic trickling filter on the upper section, and as the openings 9 in the lower section function to meter the water from the various areas of the tray, the openings closet to the pump being the smallest and the openings gradually increasing in size as the distance increases from the pump whereby the reduced action of the pump at the more remote points is compensated by the larger openings. At the same time the tapered formation of the bed of filter material 26 provides additional compensation at the remote points on the tray thereby tending to balance the flow through the upper section and reducing the possibility of a short circuiting water flow concentration adjacent the pump. Upon discharge of the water into the chamber 38 a flow will take place through the openings 61 into the bottom of the filter cartridge 41 by way of the openings 55 therein, with the filtered water being discharged from the top of the cartridge and flowing over the discharge spout to return to the aquarium.

It will be noted that as the cartridge accumulates material therein, withdrawn from the water, as the flow through the tertiary filter cartridge diminishes, the increased resistance across the tertiary filter will result in a raising of the water level in the chamber 38 resulting in an increase in the head pressure on the filter, whereby the structure tends to be self-compensating, tending to maintain a relatively uniform filtering action.

In the event the tertiary filter reaches the point where the flow is substantially blocked the water level in the chamber 38 is free to rise to a point where it can overflow the top edge 62 of the wall 37 to by-pass the filter cartridge and discharge directly to the discharge spout 7 thereby eliminating any possibility of an overflow exteriorly of the tank.

INTERNAL FILTER STRUCTURE As previously mentioned, the embodiment of the invention constructed for disposition within the aquarium tank may be employed with or without an undergravel filter, such as that described in connection with the external filter structure, with the only difference being a slight modification of the body or housing and corresponding changes in the water inlet openings. FIGS. 9-12 illustrate the general construction of the internal filter and the arrangement of the fluid inlets when used without an under-gravel filter structure while FIG. 13 illustrates the modifications therein when employed with such activating trickling filter.

Referring to FIGS. 9-12, in this. embodiment of the invention the casing or body member 101 is designed to be positioned in a corner of the aquarium tank and thus is provided with two vertically extending walls 102, extending substantially at to one another, which are connected to a diagonally extending front wall 103 by respective intermediate connecting walls 104. The walls 102, 103 and 104 are joined to a bottom wall 105 and the open upper end of the structure is closed by a cover member 106 having downwardly extending peripheral flange portions 107, with the configuration of the respective walls being such that the body member and cover form a truncated prism, with the cover 106 extending upwardly at an angle and forming an apex at the juncture of the walls 102. Disposed in the casing 101 are a pair of upwardly extending partition walls 108, which extend in parallel relation with respect to the walls 104, anddisposed between walls 102, 103 and partition walls 108 is a filter cartridge, indicated generally by the numeral 109, which is provided with side walls .111, 112 and 113 extending in substantially parallel relation with respect to the corresponding walls 102, 103 and 108. The side walls of the cartridge are connected by a bottom wall 114 which is provided with a plurality of water inlet openings 115 therein. 7

The internal construction of the cartridge 109 is similar to the cartridge 41 with the main difference being that the flow through the cartridge 109 is in a reverse direction to that in the cartridge 41. In the latter the water How is upwardly through the cartridge while in the cartridge 109 the flow is from the top downward through the bottom. As a result, the arrangement of the fine and coarse filter materials is reversed, the fine filter material 57 being disposed adjacent the bottom wall 115 and retained in position by a porous layer 58 of plastic foam or the like followed by a separating strip 56, a layer of coarse filter material 55 and a retaining porous layer 54 of foam plastic or the like.

discharge port 16', a shoulder 18 andwater inlet opening 17'. The latter communicating with the waterreceiving chamber 119 disposed below the bottom 105 of the cartridge.

As clearly illustrated in FIG. 11, to provide space for the pump 3' the walls 111 are connected at their converging edges by a semi-circular wall 121, which is cooperable with the intersecting portions of the walls 102 to, form the space for the pump 3f, with the latter having a pair of horizontally extending reinforcing members 122, each of which has a configuration which is substantially complemental to that formed by the walls 121 and adjacent portions of the walls 102, thereby effectively sealing such space with respect to the flow of water therethrough. The cartridge 109 is supported on a pair of abutments or legs 123 which are disposed adjacent the bottom 105 and frong wall 103, as clearly illustrated in FIGS. 10 and 11, with the rear portion of the cartridge being supported on a leg member 124 formed on the pump base 118. Thus as the pump 3' is not permanently mounted in the casing 101, by applying upward force to the pump structure it may be raised, carrying with it the cartridge 109, the pump in effect forming a handle facilitating removal and insertion of the cartridge.

As illustrated in FIG. 10', the tubes 14' and 15' extend through cooperable openings in the cover member 106, which is provided with an additional, relatively small opening 125 adjacent the juncture of the cover member and the walls 102, whereby such opening is at the highest point of the casing interior and is adapted to permit an egress of air therethrough when the filter is initiallyimmersed in an aquarium, thereby preventing the trapping of air within the upper portion ofthe filter.

As will be apparent from a reference to FIGS. 9 and 12, the filter therein illustrated, being designed for use without an under-gravel trickling filter, is provided with water inlet openings 126 in the side walls 104, adjacent the lower portion of the latter, whereby water is free to flow into the water inlet chambers 127 defined by the respective pairs of walls 104 and 108 and adjacent por tions of the walls 102 and 103 with such water flowing upwardly over the weirs formed by the wall 108 to the top of the cartridge 109. The water may then flow downwardly through the cartridge to the chamber 119 therebelow defined by the casing bottom 105, cartridge bottom 109 and adjacent portions of the side walls 102, 103 and walls 108, from which the water is exhausted through the eductor pump 3', the water entering the opening 17" and flowing upwardly through the tube 14'. The upper end of the latter may terminate short of the surface of the tank water and thus is operative to directly return the filtered water to the tank.

In the embodiment illustrated in FIGS. 9-13, the easing interior is provided with ribs for supporting and reinforcing the walls 108 and to close the space between the walls 113 of the cartridge and adjacent walls 108, the cartridge may be provided with horizontally extending flanges or lips 127 which effectively seal the space between the walls 108 and the walls 113, thereby preventing a by-pass flow of water therethrough.

In operation of the internal filter structure, upon supply of air to the tube 15, such air will rise in the tube 14', resulting in an eductor action carrying a flow of water upwardly through the tube, which flow will in turn create a flow through the filter, with the water entering the inlets 126 passing upwardly in the respective chambers 127, down through the filter to the chamber 119 and into thepump 3'.

In the event an internal filtersuch as illustrated in FIGS. 9-11, is tobe employed with an under-gravel trickling filter similar to that illustrated in FIGS. 1-6, the construction of the under-gravel filter may be substantially as previously described with the exception of the construction of the corner portion at which the pump 3 is located.

in this case, as illustrated in FIG. 13, the lower section 6' of the tray structure 1' is provided with an opening therein of a size to receive the filter casing 101 with the tray section having a downwardly depending wall 129, which is disposed adjacent the periphery of the filter structure and is provided with an opening 131 therein located adjacent each ofthe walls 104 of the filter, with each of the latter walls having a single coopcrable water inlet opening 126' aligned with the corresponding opening 131, the openings 126' each taking the place of the plurality of openings 126 in the respective walls 104 illustrated, for example, in FIGS. 9 and 12. i

As illustrated in FIG. 13, the side walls 104 and 103 of the casing 101 may be provided with outwardly extending flanges 132 adapted to seat on the adjacent floor 8 of the lower tray section 6, with the upper tray section 5 terminating adjacent the flange 132 as clearly illustrated in FIG. 13. i

In this construction the operation of the under-gravel filter would be substantially the same as that previously described in connection with the external filter structure with the finally filtered and polished water being containing filter material having the greatest particle size, and after flowing through the latter is passed through thefilter material of lesser size, which I have found contributes substantially to an exceptionally long filtering cycle without excessive clogging, etc.

It will be apparent that in replacing the filter cartridge of the internal filter the entire filter casing may be readily lifted up from the tank and upon removal of the cover, the cartridge may be readily withdrawn by raising the pump structure as previously described. Following insertion of a new cartridge and return of the cover, the filter casing may be readily returned to its original position in the'corner of the tank.

It will be apparent that, while I have illustrated an internal filter structure having a generally triangular cross-section, that the present invention may be readily embodied in filter structures of different configuration as, for example, having a rectangular cross-section and a height greater than its other dimensions, Such a construction is particularly suitable where the filter is fabricated in a relatively small size adapted for use in tanks, for example, of around 5 gallons, etc., whereas in larger tanks it may be desirable to employ a correspondingly larger filter, in which case the triangularshaped structure may appear less bulky in the tank than a large'filter of rectangular construction.

It will be noted from the above description that where the complete system is employed the aquarium is, in effect,'provided with a complete, self-contained sewage disposal system which will provide bio-filtration as previously described, resulting in drystal clear aquarium water, heretofore unobtainable in small aquariums. While I have illustrated the purification system and filter structures in embodiments suitable for small home aquariums and the like, it is believed obvious that the present invention is not limited to comparatively small aquariums and'may be quite readily adapted to large aquarium tanks and the like, in which case the size'ofthe filter elements would be proportionately increased and the tray structures, etc., suitably fabricated for use in the surrounding conditions to which it is to be subjected. Forexample, the tray structure for the under-gravel filter may be fabricated from metal or the like to provide adequate strength for the particular application.

MODIFIED UNDERWATER-GRAVEL FILTER FIGS. 14 through 17. illustrate a modified construction of the underwater-gravel filter. In this construction the reference-numeral 1 indicates generally a filter structure comprising an upper section, indicated generally by the reference numeral'S and a lower section indicated generally by the reference numeral 6, formed from suitable material such as a suitable plastic or the like, and thus capable of being readily fabricated in'a suitable molding operation. The lower section 6 is formed with a generally horizontally extending planar wall member or flow 8' enclosed in peripheral edge walls 7, integrally formed therewith. As clearly illustrated in FIGS. and 16, the wall member 8 intersects the peripheral walls 7 intermediate the top and bottom edges thereof to provide wall portions 7a depending downwardly from the wall member 8 and portions 7b extending upwardly from such wall member.

As illustrated in FIG. 2, the wall member 8 is provided with an opening 17b therein, adjacent one corner of the structure which is adapted to form a water discharge opening through which water disposed below the wall member 8 may flow. The wall member 8 is likewise provided with a plurality of openings 9 therein which are graduated in size, being disposed at a greater distance from the discharge opening 17a than the smaller openings, the size and arrangement of the openings preferably being such that, in the manner previously described, an equalization of water flow.

through the wall member 8 is promoted.

The upper section 5 is adapted to be disposed on the lower section and comprises a generally planar wall member or floor 21 which is provided with downwardly depending peripheral walls 24 which are adapted to rest upon the upper face of the wall member 8 and thus support the wall member 21 therefrom with the section 5 thereby being, in effect, nested in the section 6. The wall memberv 21 is provided with a pair of openings 17b and 1717' which are likewise disposed adjacent respective corners of the section 5 and so positioned with respect to the positioning of the opening 17a in the wall member 8 that either of the openings 17b or 17b may be disposed in cooperable alignment with the opening 17a by suitable orientation of the section 5 in the section 6, the sections, as illustrated, being of a substantially square configuration whereby the'upp er section may be nested in the lower sectionwith any side wall 24 of the upper section disposed adjacent any side wall portion 7 of the lower section. Consequently, either of the openings 17b or 17b may'be positioned as illustrated in FIG. 15 for cooperable alignment with the opening 170, thus enabling the disposition of the discharge opening 17a at either the left hand side of the tray structure, as viewed in FIG. 14, or at the opposite side thereof without requiring separate right and left handed sections. The opening 17b or 17b not disposed in cooperable alignment with the opening 17a may be suitably closed by a snap-in type of plug 133 or the like.

The wall member 21 is provided with a plurality of openings or slots 23, substantially uniformly arranged over the area of the wall members 21, which have a transverse width which is less than the minimum size of the discrete particles 27 of filter material, such .as aquarium gravel, to be disposed thereon whereby such discrete particles will not pass through the wall member. As illustrated in FIG. 16 these slots may be triangular-in transverse cross section with the side walls defining the same thus diverging from the upper face of the wall member.

Disposed in the intermediate chamber between the wall members 8 and 21 is a layer 134 of suitable material, for example, a porous foam plastic, such as the commonly used polyurethane foams on the market and as illustrated in FIGS. 14 and 16, a plurality of downwardly depending projections or feet 25 may be provided on the lower side of the wall member 21 for providing intermediate support of the latter, such projections readily substantially completely compressing the material of the layer 134 thereat.

The flow of water from thespace below the wall member's is adapted to be effected by suitable means such as an air pump indicated generally by the one another. Thefitting 135 is provided with a water discharge bore 137 and an air inlet bore 138 adapted to be respectively connected to the water discharge tube 14 and an air supply tube 15. The fitting 135 is provided with the small airpassageway l6 connecting the lower end of the bore 137 with the borel38, thus forming an air operated pump generally corresponding to the pump illustrated in FIGS. 4 and 5.

Operation is similar to the construction of FIGS. 2 and 3. As illustrated in FIG. 16 the surface of the wall member 21 is adapted to receive a layer of discrete filter material such as aquarium gravel 27 and in operation water will flow through'the gravel, the slots 23, porous layer 13, openings 9, to the plenum chamber below the wall member 8 and eventually discharged through the pump 3.

As in the construction ofFIGS. 2 and 3, the arrangement and size of the openings 9 are such that in operation, a reasonably effective equalization of water flow through the structure over the entire area thereof achieved, i.e., the water flow through the gravel is reasonably uniform throughout the area thereof.

Where the structure is made in the form of modules, rather than a single structure for each different'size tank, a plurality of such structures may be employed with the discharge openings in the respective structures being located at adjacent corners so that they may conveniently be connected to a common additional filter structurefThis may be readily accomplished by merely rotating the lower section relative to the upper section, for example, when viewed in FIG. 14, by rotating the lower section through 90 in a clockwise direction to position the bore 17b in cooperable alignment with the bore 137. Two adjacent structures may be suitably connected or interlocked in a very simple manner by utilizing suitable connecting means, for example, one or more clips, or channel members 139 which may be of elongated construction and U-shaped in transverse cross section as illustrated in FIG. 17. This member 139 may be constructed of relatively thin walled material such as plastic, for example, as an extrusion, and suitably proportioned to be snapped or sprung over the abutting wall portions 7b ofthe adjacent structures thus firmly interlocking the latter in position.

' It will be noted that the construction is exceedingly simple, enabling the utilization thereof with ordinary Having thus described my invention it will be obvious to those skilled in the art from the disclosure herein given that various immaterial modifications might be made in the same without departing from the spirit of my invention, hence I do not wish to be understood as limiting myself to the exact form, arrangement and combination of parts herein shown and described or used as mentioned.

lclaim:

1. An aquarium undergravel trickling filter device comprising a tray-like structure adapted to be disposed aquarium gravel with the techniques employed being similar to that currently employed without a tray structure or with prior types of tray structures.

It might further be mentioned that while the undergravel filters and the final filter constructions herein illustrated, employing cartridge elements, are particu larly adapted to use with the specific under-gravel filter illustrated, the latter could, for example, be-employed with filter structures utilizing bulk filter materials with improved results over prior filter structures designed for comparable usage.

on the bottom wall of an aquarium tank and constructed to provide a pair of generally planar upper and lower walls and support the same with the lower wall being spaced from the bottom wall of such aquarium and the upper wall being disposed above and spaced from the lower wall, said upper wall being adapted to receive a layer of discrete filter material thereon and provided with openings therein arranged substantially uniformly over the area of said wall for the passage of water therethrough, which openings are smaller, in width than the size of the particles of said discrete'filter material, said lower wall having a. water discharge opening therein and other openings therein of more than one size, with the size of such other openings increasing at increasing distances from said discharge opening and tending to effect an equalization, over the wall area, in the volume of water passing therethrough.

2. A device according to claim 1, wherein said tray- ]ike structure comprises an upper section and a lower section, said upper wall comprising a part of the upper section and the lower wall comprising a part of the lower section.

3. A device according to claim 2 wherein said sections having a square configuration, the wall member of the lower section having said discharge opening therein adjacent a corner thereof, the wall member of the upper section having a pair of openings therein disposed adjacent respective adjacent corners of the upper section, either one of which openings may be.

cooperably aligned with the discharge opening in the wall member of the lower section in dependence upon relative orientation of the respective sections, and means for closing the other opening of such pair.

4. A device according to claim. 1 wherein the upper face of said upper wall inclined downwardly towards said dischai'ge opening whereby the bed of filter material increases in depth toward such opening.

5.A device according to claim 1 wherein said lower section is provided with peripheral side walls extending upwardly therefrom, in which the upper section is nested, and wherein a pair of said tray structures are employed in side-by-side relation with the adjacent peripheral walls of the respective lower sections disposed in abutting relation, and connecting means for said structures having an inverted U-shape in transverse cross section mounted on the abutting peripheral walls with the latter disposed between the leg portions of said U-shaped means.

6. A device according to claim 1, wherein said upper wall is adapted with openings constructed and arranged to retain a layer of filter material thereon having a par ticle size less than that of the aquarium gravel to be employed therewith, said structure having peripheral walls extending above the upper face of said upper wall with the upper edges of said peripheral walls lying in a common plane which is to define the top surface of the bed formed by saidtilter material.

7. A device according to claim 6 wherein said tray structure comprises upper and lower sections, with said peripheral walls forming a part of the lower section, and said upper wall forming a part of the upper section.

8. A device according to claim 7 wherein the upper face of said upper wall is inclined relative to said upper edges of said peripheral walls downwardly towards said discharge opening whereby the bed of filter material increases in depth toward said discharge opening.

9. A device according to claim 6 wherein said upper walls is provided with a plurality of upstanding ribs, the upper edges of which lie in said plane, each of said ribs extending on a line on said upper face which lies in a plane extending parallel tosaid first-mentioned plane.

10. A device according to claim 9, wherein said peripheral wallsare formed integrally with the lower section and said ribs are formed integrally with the upper section, said upper and lower sections being provided with downwardly extending portions constructed to respectively engage the .lower section and the bottom of the aquarium tank for transmitting forces acting on the upper section of said tray structure to the lower section thereof and from the latter to:the bottom of the aquarium tank.

11. A device according to claim 1, comprising in further combination, a layer of porous material substantially laterally filling the space between said upper and lower walls, said upper wall having a discharge opening therein cooperable with said discharge opening in the lower wall through which water passing through the lattermay be discharged.

l2. A'de vice according'to claim 11, comprising in further combination a pump structure adapted to be seated on said lower section and having a portion exv tending through said cooperable opening in said upper wall, said pump structure having a water inlet opening in said portion communicating with the space below said lower wall.

13. A device according to claim 11 wherein said lower section is provided with peripheral side walls extending upwardly therefrom, in which the upper section is nested, and wherein a pair of said tray structures are employed in side-by-side relation with the adjacent peripheral walls of the respective lower sections disposed in abutting relation, and connecting means for said structures, having an inverted U-shape in transverse cross-section, mounted on the abutting peripheral walls with the latter disposed between the leg portions of said U-shaped means.

14. A device according to claim 11 wherein said lower section is provided with peripheral side walls extending upwardly therefrom, in which the upper section is nested, the upper section having peripheral side walls extending downwardly therefrom constructed to seat on the lower wall.

15. A device according to claim 11 wherein said sections having a square configuration, the wall member of the lower section having said discharge opening therein adjacent a comer thereof, the wall member of the upper section having a pair of openings therein disposed adjacent respective adjacent corners of the upper section, either one of which openings may be cooperably aligned with the discharge opening in the wall member of the lower section in dependence upon relative orientation of the respective sections, and means for closing the other opening of such pair.

16. A device according to claim 14 wherein said side walls of the lower section also extend downwardly from such wall member, constructed to seat upon the bottom of such an aquarium.

17. A device according to claim 16 wherein said lower section is provided with downwardly'depending flanges which extend in diverging directions from adjacent said discharge opening.

18. A device according to claim 17 wherein said layer of porous material comprises a sheet of porous plastic foam of a size to nest in the space defined by the side walls of said upper section, and filling at least the greater part of the space between said upper and lower walls. I 

1. An aquarium undergravel trickling filter device comprising a tray-like structure adapted to be disposed on the bottom wall of an aquarium tank and constructed to provide a pair of generally planar upper and lower walls and support the same with the lower wall being spaced from the bottom wall of such aquarium and the upper wall being disposed above and spaced from the lower wall, said upper wall being adapted to receive a layer of discrete filter material thereon and provided with openings therein arranged substantially uniformly over the area of said wall for the passage of water therethrough, which openings are smaller in width than the size of the particles of said discrete filter material, said lower wall having a water discharge opening therein and other openings therein of more than one size, with the size of such other openings increasing at increasing distances from said discharge opening and tending to effect an equalization, over the wall area, in the volume of water passing therethrough.
 1. An aquarium undergravel trickling filter device comprising a tray-like structure adapted to be disposed on the bottom wall of an aquarium tank and constructed to provide a pair of generally planar upper and lower walls and support the same with the lower wall being spaced from the bottom wall of such aquarium and the upper wall being disposed above and spaced from the lower wall, said upper wall being adapted to receive a layer of discrete filter material thereon and provided with openings therein arranged substantially uniformly over the area of said wall for the passage of water therethrough, which openings are smaller in width than the size of the particles of said discrete filter material, said lower wall having a water discharge opening therein and other openings therein of more than one size, with the size of such other openings increasing at increasing distances from said discharge opening and tending to effect an equalization, over the wall area, in the volume of water passing therethrough.
 2. A device according to claim 1, wherein said tray-like structure comprises an upper section and a lower section, said upper wall comprising a part of the upper section and the lower wall comprising a part of the lower section.
 3. A device according to claim 2 wherein said sections having a square configuration, the wall member of the lower section having said discharge opening therein adjacent a corner thereof, the wall member of the upper section having a pair of openings therein disposed adjacent respective adjacent corners of the upper section, either one of which openings may be cooperably aligned with the discharge opening in the wall member of the lower section in dependence upon relative orientation of the respective sections, and means for closing the other opening of such pair.
 4. A device according to claim 1 wherein the upper face of said upper wall inclined downwardly towards said discharge opening whereby the bed of filter material increases in depth toward such opening.
 5. A device according to claim 1 wherein said lower section is provided with peripheral side walls extending upwardly therefrom, in which the upper section is nested, and wherein a pair of said tray structures are employed in side-by-side relation with the adjacent peripheral walls of the respective lower sections disposed in abutting relation, and connecting means for said structures having an inverted U-shape in transverse cross section mounted on the abutting peripheral walls with the latter disposed between the leg portions of said U-shaped means.
 6. A device according to claim 1, wherein said upper wall is adapted with openings constructed and arranged to retain a layer of filter material thereon having a particle size less than that of the aquarium gravel to be employed therewith, said structure having peripheral walls extending above the upper facE of said upper wall with the upper edges of said peripheral walls lying in a common plane which is to define the top surface of the bed formed by said filter material.
 7. A device according to claim 6 wherein said tray structure comprises upper and lower sections, with said peripheral walls forming a part of the lower section, and said upper wall forming a part of the upper section.
 8. A device according to claim 7 wherein the upper face of said upper wall is inclined relative to said upper edges of said peripheral walls downwardly towards said discharge opening whereby the bed of filter material increases in depth toward said discharge opening.
 9. A device according to claim 6 wherein said upper walls is provided with a plurality of upstanding ribs, the upper edges of which lie in said plane, each of said ribs extending on a line on said upper face which lies in a plane extending parallel to said first-mentioned plane.
 10. A device according to claim 9, wherein said peripheral walls are formed integrally with the lower section and said ribs are formed integrally with the upper section, said upper and lower sections being provided with downwardly extending portions constructed to respectively engage the lower section and the bottom of the aquarium tank for transmitting forces acting on the upper section of said tray structure to the lower section thereof and from the latter to the bottom of the aquarium tank.
 11. A device according to claim 1, comprising in further combination, a layer of porous material substantially laterally filling the space between said upper and lower walls, said upper wall having a discharge opening therein cooperable with said discharge opening in the lower wall through which water passing through the latter may be discharged.
 12. A device according to claim 11, comprising in further combination a pump structure adapted to be seated on said lower section and having a portion extending through said cooperable opening in said upper wall, said pump structure having a water inlet opening in said portion communicating with the space below said lower wall.
 13. A device according to claim 11 wherein said lower section is provided with peripheral side walls extending upwardly therefrom, in which the upper section is nested, and wherein a pair of said tray structures are employed in side-by-side relation with the adjacent peripheral walls of the respective lower sections disposed in abutting relation, and connecting means for said structures, having an inverted U-shape in transverse cross-section, mounted on the abutting peripheral walls with the latter disposed between the leg portions of said U-shaped means.
 14. A device according to claim 11 wherein said lower section is provided with peripheral side walls extending upwardly therefrom, in which the upper section is nested, the upper section having peripheral side walls extending downwardly therefrom constructed to seat on the lower wall.
 15. A device according to claim 11 wherein said sections having a square configuration, the wall member of the lower section having said discharge opening therein adjacent a corner thereof, the wall member of the upper section having a pair of openings therein disposed adjacent respective adjacent corners of the upper section, either one of which openings may be cooperably aligned with the discharge opening in the wall member of the lower section in dependence upon relative orientation of the respective sections, and means for closing the other opening of such pair.
 16. A device according to claim 14 wherein said side walls of the lower section also extend downwardly from such wall member, constructed to seat upon the bottom of such an aquarium.
 17. A device according to claim 16 wherein said lower section is provided with downwardly depending flanges which extend in diverging directions from adjacent said discharge opening. 